Keels absent. Inframedian plates bent at their midline above pectoral fin to form ridge. Dorsal plates bent dorsally below dorsal fin to form very slight ridges that converge at adipose fin, dorsal surface flat between ridges. Five rows of plates on caudal peduncle. Abdomen almost fully plated in largest specimen available, naked only in small area just posterior to insertion of pectoral-fin spine and in a wide band between insertions of pelvicfin spines; smaller individuals with various degree of plating. First anal-fin pterygiophore exposed to form a platelike structure. A pair of lateral plates converging at midline between anus and exposed first anal-fin pterygiophore. 25-26 (mode = 26) plates in the median series.

Frontals, infraorbitals, nasals, pterotic-supracleithra, sphenotics, and supraoccipital, supporting odontodes; opercle supporting odontodes in juveniles but not in adults, posterodorsal corner of opercle covered by one or two plates in adults. Odontodes on lateral plates not enlarged to form keels. Hypertrophied cheek odontodes 18-36, longest reaching first inframedian plate in adults. Cheek plates evertible to approximately 90° from head. Odontodes on tip of pectoral-fin spine slightly hypertrophied.

Color. Color same for live and preserved specimens except that live specimens have thick, orange bands at edge of dorsal and caudal fins. Background color gray-brown. Dorsal surface with four faint saddles, first below second and third dorsal-fin rays, second below last two dorsal-fin rays and slightly behind dorsal fin, third below adipose fin, and fourth at end of caudal peduncle. First two saddles combine at lateral line to form dark patch that extends from second saddle almost to pterotic-supracleithrum anteriorly and to ventral margin of inframedian plate row. Head plates and bones and plates of the nuchal region and dorsal, supramedian, and median plate rows to below dorsal fin completely outlined in black. Dorsal fin gray with wide distal orange band in life. Caudal fin spines gray, caudal fin with distal orange band in life. Ventral surface lighter than sides, saddles three and four contiguous across ventral surface in juveniles, but much lighter ventrally, and not contiguous in the largest specimens. Pectoral and pelvic fins gray. Juveniles colored similarly to adults, but dark colors more intense.

Sexual dimorphism. Males of PeckoltiaZBK generally have hypertrophied odontodes on the lateral plates, but this was not observed in P. cavaticaZBK .

Range. Collected from two localities around the Macushi village of Massara near Anai in the Rupununi River (Fig. 3). Found in areas with a large number of lateritic rocks. Most specimens were removed from holes in the rocks.

Etymology. From the Latin cavaticus meaning born or living in caves. In reference to the fact that most of the specimens were captured from holes in lateritic rocks, and the fact that it is likely that such holes are where this species breeds.

Discussion

During the rainy season, the Rupununi Savanna floods, connecting the Takutu (Amazon) and Rupununi (Essequibo) rivers around the Pirara River and Lake Amuku (Takutu River drainage), providing a potential mechanism for dispersal of fishes between the Amazon and Essequibo basins (Lowe-McConnell; 1964). Perhaps as a consequence of the seasonal connection between the Takutu and Rupununi, nearly all hypostomine loricariids that we collected in the Rupununi River were also found in the Takutu. The only exception is P. cavaticaZBK , which is replaced by P. braueri in the Takutu. Based on the derived presence of orange bands in the dorsal and caudal fins, it is likely that Peckoltia braueri and P. cavaticaZBK are sister species. The divide between the Rupununi and Takutu has been sufficient for the populations represented by P. braueri and P. cavaticaZBK to become distinct despite the fact that P. braueri is found in the Pirara River (the main point of contact between the two river basins). The fact that the ancestor of P. braueri and P. cavaticaZBK speciated despite the current connection between the Takutu and Rupununi suggests that patterns of dispersal and isolation between these two basins may be complex, and that the portal represented by the flooded Rupununi Savanna may not be a dispersal route for all species.

Le Bail et al. (2000) picture a species that they label as Hemiancistrus aff. braueriZBK . The specimen pictured is mottled with two full dark bands and one incomplete dark band in the caudal fin, and three dark bands in the dorsal fin, and it doesn’t have the head and nape plates outlined in black. The pictured specimen is live, but it does not have the orange band in the dorsal and caudal fins. In coloration, the specimen is much more similar to Peckoltia vittata .

Currently, the taxonomy of PeckoltiaZBK and closely related genera such as HemiancistrusZBK is confused. Isbrücker et al. (2001) pull two genera from PeckoltiaZBK , AncistomusZBK for P. snethlagae (Steindachner, 1911) and SophiancistrusZBK for P. arenaria (Fowler, 1940) and P. ucayalensis (Eigenmann and Allen, 1942) ; however, these genera have not been accepted (Fish-Muller, 2003; Armbruster, 2004). Cardoso and Lucinda (2003) provide characteristics that attempt to separate PeckoltiaZBK and HemiancistrusZBK ; however, they conclude that there are no useful characteristics to separate the genera. The confusion of the two genera is clear when examining P. braueri , which is considered either HemiancistrusZBK (Cardoso and Lucinda, 2003) or PeckoltiaZBK (Fisch-Muller, 2003).